Chicago Weather

When is the real first day of spring? The answer is complicated

The answer depends on which way you look at it, but as of Wednesday, it won't matter -- spring is here

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Is it officially spring yet?

The answer to that question depends on which way you look at it, but as of Wednesday, every scenario points to yes.

The first official day of spring can be multiple dates.

For those who focus on meteorological spring, the season actually started on March 1. For those looking for the spring equinox, 10:06 p.m. Tuesday marked the official start.

And for those who prefer the first full day of spring after the equinox, well, Wednesday is it.

So why are there so many options?

The reason meteorologists have a different definition for spring is simple: the date never changes. Unlike astronomical spring, which doesn’t fall on the same date every year, the changing of the seasons for meteorologists always fall on the same dates. Winter begins on Dec. 1, spring begins on March 1, summer begins on June 1, and fall begins on Sept. 1.

That ensures consistency in recordkeeping, and just about mirrors the changing of the seasons in terms of temperatures and weather conditions.

The reason astronomical spring changes dates is because the Earth doesn’t take exactly 365 days to orbit the sun. In fact, the common wisdom is that it takes 365 and one-quarter days, which is why we have leap years, but that measurement isn’t precise either, leading to the seasons changing date very slightly each year.

Astronomical spring begins when the sun crosses the celestial equator, moving toward the Northern Hemisphere as opposed to the Southern Hemisphere.

No matter which definition you choose now, however, it is officially spring - though it might not feel like it in the Chicago area.

According to the NBC 5 Storm Team, winter-like temperatures in the 20s and 30s marked the start of the new season, despite an unseasonably mild winter that saw weeks in the 50s and 60s.

Wednesday will remain chilly, with highs reaching only into the 30s and 40s, where they will stay Thursday before a system could potentially bring snow to the region.

"A system moves in late Thursday into Friday morning, and yes, you could see snow," NBC 5 Storm Team Meteorlogist Alicia Roman said.

Roman noted a snow-rain mix was expected to continue into Friday morning. According to the NWS, "minor, slushy" accumulations could occur closer to the Illinois-Wisconsin state line.

With temperatures Friday remaining in the 30s and 40s, "winter weather is back in the forecast as we wrap up the work week," Roman said.

According to the NWS, Saturday will remain on the cool side, but with more sunshine.

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